Certificate of correction



June 17, 1930. 1 I ERLENBACH 1,764,249

PROCESS OF TREATING SAWDUSI Filed Aug. 12, 1926 5 exiffor liquid and solid Ina/fer Ifi/n saw dusf pulp recepfacle J'nvenlar:

4.; A rm/FWEYS 1 Patented June 11, 1930 EDGAR ERLENBACH, OI BERLIN, GERMANY success or 'rnne'rme sawnusr .Applicat'ion filed August 12, 1926, Serial No. 128,911, and in Germany August 18, 1925.

Iii the wood industry large quantities of saw dust are formedwhich often-times are a cumbersome waste product which mainly is only used as fuel, although it is known that by heating itunder high pressure valuable pumping action. .J

products such as acetic acid, methyl alcohol, acetone can be obtained therefrom together with tarry substances.

This invention has for its purpose to make use of this fact in an industrialprocess.which process comprises theforming of a pulp rom such saw dust with an aqu eous liquid, the transporting of same through a high pressure apparatus wherein it is subjected to elevated temperature of about 350 C. at the pressure corresponding to such temperature whichpressur'e is below 200 atmospheres at the temperature of 350 6., and the recovering of the productsjwhich are formed under such conditions. The terms high pressure apparatus and Fpressure proof apparat-us as used in the specification and claims are intended to denhte apparatus adapted to withstandhigli pre ssures'up to about 250 atmospheres. t will be obvious that the pressure .existin in the system any given'temperature wi l'correspond to the vapor pressure of the aqueoufmedium at that temperature.

The'esfsential point this invention consists therein that it has been vfoimd to be practicable to; continuously move a. watery saw dust pulp through a conduitjby'a suitable The'fridtion resistanceofth regressing movement. with argely depends uponthe na dust pulp and upon the aqueous q in the saw, dust is suspended.

li visable to use a. gaustic alkali solution herthe aqueousliquid with which-the pulpg s formed suchcaustic alkalifsolutibn ".forxiiing f }igap-* like compounds with certain constituents-bf j the sawdust which have the'eflect of lubri-f cents. The presence of caustic alkali with-- in' the reactionfsystem is'moreover advantageous for the reaction process in this regard that acetic acidjormedin the process"- is bound to alkali so that the damaging intluence-of the acid on the reaction apparatus is avoided.

The quantity of added'alkalishould beiso v calculated that good lubrication is secured by the combined action of the added alkali and water. Suitable amounts of water and alkaliare given in the following examples.

The process is illustrated by the following specific examples.

Ezvample 1 Air dry saw dust of beech trees is intermixed with four times its weight of water and pressed by a suitable pumping device through a high pressure system with such velocity that it is subjected about two hours to a temperature of 300" C. at about at- Example .2

Air dry saw dust of beech trees is mixed with a solution of 50% of its weight in potassium hydroxid in 80% of its weight, 1n

water'and the mixture is driven through a pressure proof apparatus with such velocity that it is exposed for about two hours to a temperature of about. 300 C. at about atmospheres; this temperature and pressure being the maximum within the system. The

velocity corresponding to a reaction perioda of two hours'will vary directly with the capacity of the part of the high pressure systeruexposed to heat. Thus if the capacity ofj'sy'stem is 50 gallons the velocity necesto obtain a two hour reaction period yffiyield of 11% potassium acetate, 3% ethylalcohol, 1 acetone calculated on the weightof the air dry's'aw dust and a good -dealof tar-is obtained. u

The process may be carried out in the apparatus schematically illustrated in the an nexed "drawing wherein l, designates a bin'or .receptacle for. the aqueous sawdust pulp; 2 1s would obviously be 25 gallons per hour. v

a pumping device which on its suction stroke opens a valve 3 and keeps closed a valve 4 provided in a channel 5 connecting receptacle 1 with a heating device or kiln 6 through which the ,saw dust pulp is moved 'by the pressure exerted thereon by the pump- 2. Within the kiln 6 the saw dust is decomposed to solid carbonuaceous and gaseous matter under the influence of heat and pressure with simultaneous formation of acetic acideither as free acid if the saw dust pulp is formed with pure water, or as acetate of alkali if the pulp is formed with an aqueous solution of caustic alkali-of methyl alcohol and acetone. The reaction products leaving the kiln pass'through conduit 7 and enter a receptacle 8 wherein solid and liquid components settle down and can be withdrawn through exit 9 whereas the gaseous and vaporous constituents escape through conduit 10.

What I claim is 1. A process of decomposing sawdust which comprises transporting sawdust as an aqueous pulp for about two hours through a pressure proof system "at a temperature at which the sawdust is appreciably decomposed and at a superatmospheric pressure corresponding to the vapor pressureof the aqueous pulp at said temperature.

2. A process of decomposingsawdust which comprises transporting sawdust as an aqueous pulp for about two hours containing caustic alkali through a pressure proof system at a temperature at which the sawdust is appreciably decomposed and at a superatmospheric pressure corresponding to said temperatur 3. A process wof decomposing sawdust which comprises pumping sawdust as an aqueous pulp for about two hours through a pressure proof system at a temperature at which the sawdust is appreciably decom posed andat a superatmospheric pressure corresponding to the vapor pressure of theaqueous pulp at said temperature.

In witness whereof, I afiix my signature.

DR. EDGAR ERLENBACH.

CERTIFICATE or CORRECTION.

Patent No. 1,764, 249. Granted June 17,1930, to

' EDGAR ERLENBACH.

It is hereby certified that error appears in the printed specification of the above numhered patent requiring correction as follows! Page 2, line 37, claim 2, after "corresponding tof' insert the words "the vapor pressure of the aqueons pulpat"; and that the said Letters Patent should be read with this correction thereinthat the same may conform to the record of the case in the Patent Office.

Signed and sealed this 9th day of September, A. D. 1930.

M. J. Moore, (Sea!) Acting Commissioner of Patents. 

